German published application DE 103 51 848.7 discloses a system for detecting macrodefects. The system is surrounded by a housing and subdivided into a first section, a second section, and a third section. In the second section, a table is provided that is movable in at least an X-direction and a Y-direction, onto which a wafer or a disc-shaped substrate, respectively, may be placed. An aspiration device that directs the aspirated air via an air guide is located in the first section, whereby the air guide comprises several air baffles so that an air stream is directed in parallel over the wafer.
DE 43 10 149 C2 discloses a device for handling disc-shaped objects at a working level of an on-site clean room. Furthermore, cartridge receptacles are provided, whose height may be adjusted in relation to the working level. Workstations for processing or inspection purposes are located at the working level. The working level is arranged above an intermediate bottom, which divides the clean room into two partial rooms stacked one on top of the other, in which an air stream component of an air stream is directed from the partial room above the intermediate bottom into the partial room below the intermediate bottom that contains the drive components. The air stream serves to ensure that none of the abraded particles produced by the drive elements reach the workstations in the working level. The air preparation apparatus comprises a housing, and its air vent is divided by circle sector-shaped windows with air baffles. Nothing is mentioned about the particular direction, routing, and/or guides for the air stream within the housing.
German patent DE 195 38 040 C2 discloses a device for generating a clean, turbulent air stream to supply on-site clean rooms. The on-site clean room is surrounded by a housing. The housing possesses an air supply on a side wall. A centrifugal fan is provided behind the air supply, by which the air reaches the interior of the device. An air outlet is provided on the wall that is located opposite the wall with the air supply. The distribution of the air stream in the interior of the on-site clean room is neither mentioned nor considered.
European patent EP 0 335 752 discloses a system for semiconductor production under clean-room conditions. The system comprises a building surrounded by walls, whereby clean-room conditions pertain in a part of the building. The air is fed into the clean room via filters. Holes in the floor of the clean room direct the clean air, for example, to another part of the facility. Nothing is disclosed about how the air stream is routed or directed.